This invention relates to a thermosetting resin composition affording a hardened surface on which a clear mark, sign, letter or the like pattern can be marked with a laser beam. The present invention is also directed to a laser beam marking method.
There is a known marking method in which a laser beam is irradiated on a surface of a shaped body containing a laser marking material, so that the irradiated portions are colored or discolored to form a desired, discriminative pattern on the surface of the shaped body. Such a laser marking material is a lead compound, copper oxalate, cobalt oxalate, aluminum acetylacetone, bismuth oxalate, silver acetate or a metal titanate. The laser marking material is mixed in a resin matrix material and the resulting composition is shaped into a desired form.
The known composition, however, has a problem because a clear, high contrast pattern is not obtainable even if the irradiation is sufficiently carried out.